The author, who is known to the webmaster of this site, has agreed that it can be included here. Details of the process described have been independently verified, both in private, and on Forum 8. Jean-Michel Khan and 'Perspective' added confirmation of this process, and their comments are included after Mick's article. He adds some interesting detail.
Direct modes line-of-sight [ edit ] Line-of-sight refers to radio waves which travel directly in a line from the transmitting antenna to the receiving antenna. It does not necessarily require a cleared sight path; at lower frequencies radio waves can pass through buildings, foliage and other obstructions.
This is the most common propagation mode at VHF and above, and the only possible mode at microwave frequencies and above. This is the method used by cell phonescordless phoneswalkie-talkieswireless networkspoint-to-point microwave radio relay links, FM and television broadcasting and radar.
Ground plane reflection effects are an important factor in VHF line of sight propagation. Surface modes groundwave [ edit ] Main article: In this mode the radio wave propagates by interacting with the conductive surface of the Earth.
The wave "clings" to the surface and thus follows the curvature of the Earth, so groundwaves can travel over mountains and beyond the horizon. Ground waves propagate in vertical polarization so vertical antennas monopoles are required.
Attenuation is proportional to frequency, so ground waves are the main mode of propagation at lower frequencies, in the MFLF and VLF bands. Ground waves are used by radio broadcasting stations in the MF and LF bands, and for time signals and radio navigation systems.
These frequencies are used for secure military communications. They can also penetrate to a significant depth into seawater, and so are used for one-way military communication to submerged submarines. Early long distance radio communication wireless telegraphy before the mids used low frequencies in the longwave bands and relied exclusively on ground-wave propagation.
The discovery around of the ionospheric reflection or skywave mechanism made the medium wave and short wave frequencies useful for long distance communication and they were allocated to commercial and military users.
Skywave Skywave propagation, also referred to as skipis any of the modes that rely on reflection actually refraction of radio waves from the ionosphere. A radio wave directed at an angle into the sky can be reflected back to Earth beyond the horizon by these layers, allowing long distance radio transmission.
The F2 layer is the most important ionospheric layer for long-distance, multiple-hop HF propagation, though F1, E, and D-layers also play significant roles.
The layers, or more appropriately "regions", are directly affected by the sun on a daily diurnal cyclea seasonal cycle and the year sunspot cycle and determine the utility of these modes. Although the claim is commonly made that two-way HF propagation along a given path is reciprocal, that is, if the signal from location A reaches location B at a good strength, the signal from location B will be similar at station A because the same path is traversed in both directions.
However, the ionosphere is far too complex and constantly changing to support the reciprocity theorem.
The path is never exactly the same in both directions. Forecasting of skywave modes is of considerable interest to amateur radio operators and commercial marine and aircraft communications, and also to shortwave broadcasters.
Real-time propagation can be assessed by listening for transmissions from specific beacon transmitters.The Invitation: Let's start with the so-called 'invitation' to Prem Rawat to speak in a city, anywhere.
First, Rawat meets with his staff, he expresses his wishes, and they discuss potential tours and events. The Rosicrucian Cosmo-Conception Chapter XII Evolution on the Earth.
The Polarian Epoch. While the material which now forms the Earth was yet a part of the Sun, it was, of course in a fiery condition; but as the fire does not burn spirit, our human evolution commenced at once, being confined particularly to the Polar Region of the Sun..
The highest evolved beings which were to become human. Nasser with Female Saker of Race line For pure falcons going to Qatar please speak to our agent Nasser Rashed Al Naimi.
Suhail falcons center. Roots of Peace VEGETATIVE PROPAGATION TECHNIQUES Page 2 This manual was produced by Roots of Peace under USAID subcontract No.
GSFM, Task Order #M, Afghanistan Alternative Livelihoods Program. The next things to keep in mind: remove the grafting tape once the union is really well formed: the reason for this is that the caudex, as it continues to expand, tends to split up at the top of the wound, giving a less cosmetic union.
This article provides information on a few successful propagation methods that can be used on fruit trees. Tack a 1-inch piece of wood board below the union and fasten the new scion to the wood with ties.
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